New relationship between genetic risk of obesity and saturated fat intake

Limiting saturated fat intake could help those with a genetic predisposition to obesity

Limiting saturated fat could help people whose genetic make-up increases their likelihood of being obese, according to a new study from the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University.

The findings, which accounted for possible confounding factors such as age, sex, and physical activity levels, were published online on 4 June 2014, ahead of print in the Journal of the Academy of Nutrition and Dietetics.

Study method

The researchers identified 63 gene variants related to obesity and used them to calculate a genetic risk score for obesity for more than 2,800 white, American men and women enrolled in two large studies on heart disease prevention. People with a higher genetic risk score, who also consumed more of their calories as saturated fat, were more likely to have a higher Body Mass Index (BMI), the ratio of body weight to height.

“We already know there are certain genes that interact with dietary fat and affect BMI,” said senior author José M. Ordovás, Ph.D., Director of the Nutrition and Genomics Laboratory at the USDA HNRCA and a professor at the Friedman School of Nutrition Science and Policy at Tufts University.

“In the current study, we analyzed dozens of variants of those genes and other genes frequently associated with obesity risk and saw that, while total fat intake was related to higher BMI, people who were genetically predisposed to obesity and ate the most saturated fat had the highest BMIs,” Dr Ordovás said.

Genetics may influence sensitivity to saturated fats

Dr Ordovás, who is also a member of the Genetics and Pharmacology & Experimental Therapeutics graduate program faculty at the Sackler School of Graduate Biomedical Sciences at Tufts University, hypothesised that people who had these gene variants that predisposed them to obesity may be more sensitive to saturated fat, which is found mostly in fatty cuts of meats, including beef and pork, as well as butter, cheese and other high-fat dairy products.

“Little is known about the mechanisms that might explain the role of saturated fat intake in obesity,” Dr Ordovás said. “Some clinical models suggest that saturated fat might interfere with activity in the part of the brain that lets us know we’re full, in addition to a few studies in people that suggest a diet high in saturated fat interferes with satiety. More research is needed to know whether those findings would also apply to gene function,” he said.

The researchers said genetic risk score could be useful in identifying people who are predisposed to obesity and could ultimately lead to personalised dietary recommendations.

“If further research can clarify a relationship between obesity related genes and saturated fat, people with higher scores would have even more incentive to follow advice to limit their saturated fat intake as part of an obesity prevention strategy,” Dr Ordovás said.

The research was supported by the National Institutes of Health (NIH) (grant nos. 1R21AR055228-01A1, HL54776, 5R21HL114238-02, and U01 HL72524); the National Institute of Diabetes and Digestive Kidney Diseases (NIDDK) (grant nos. DK063491 and DK075030); the U.S. Department of Agriculture Research Service (USDA ARS) (grant nos. 53-K06-5-10, 58–1950-9-001, and K08 HL112845-01); the National Center for Advancing Translational Sciences, Clinical and Translational Science Institute (grant no. UL1TR000124, and the European Union Seventh Framework Programme (grant agreement no. PIOF-GA-2010-272581).